I would like to know what the consensus is on ideal water pressure for "big power" performance boats (700+hp). I have received some very diverse responses to this question. When posing the question I received these three different answers:

Response #1

Water pressure has to be at least 15-20 pounds at cruising and 25 pounds at WOT.

Response #2

5-10 at cruising and 10-15 pounds at WOT is more than sufficient. Just watch the water and oil temperatures and as long as they remain in the normal range everything is fine.

Response #3

Water pressure is not that important. Just watch your temperatire gauges and as long as they remain in the proper rnage everything is fine.

I would like some additional opinions on this matter. Thanks.

I feel that responce #2 is right on the money. More than 20 lbs and you risk blowing an intake gasket and other issues.

I'll second that motion. Response #2 seems to be the accepted values. Watch your gauges.

I vote for #2 also. 25lbs wot is entirely too much , it may work but like Biggus said ,you're risking blowing a gasket and getting water in the engine ( or out of it )

18lbs max, that cools my 1300's fine.
Loy

mine is 0 at idle ,rev motor out gear it may hit 10. running its 15-30 psi, hard its 29-32, wfo trimed up real hard its 32-36psi , therm stat keeps steddy temp.

30+ psi at WOT?? I don't think I've ever heard of water pressure that high on any boat!

I agree with response #2 as well Jeffrey. That's where my boat engines run and I haven't had any problems with cooling or head gaskets blowing or anything. My naturally aspirated 540's make around 680hp @5500rpm. My conventional deep "V" (no step or notched transom) boat has transom mounted pick-ups for the engine cooling water. We have even done a temp test with a laser temp gun and everything seemed to be consistant with no "hot spots" or anything. The laser temp guns take the guess work out of everything!

BTW, I run hoses with mechanical water preasure gauges all the way up to my dash so I can see what is going on with my water preasure constantly at every RPM level.

i have seen other post on this topic,in the scarab john at pfm put a relief valve at 40 pis so it would not spike the innercooler. my race cars have a 24 psi caps on them. chip at hustler said the psi was ok?cant remember the post ,i think it was in the q&a sec.?i remember some were around 30-32 pis some reported.the gage is were the drain cocks go. i have gotten 15 psi reving out of gear.

Is checking at the lower block drain cocks an accurate place to measure?